Coil spring guides or guidewires have been widely used for facilitating the insertion of a catheter into a vessel in the body. In some applications, a coil spring guide with a rounded tip is inserted into a vessel, a catheter is slipped about the coil spring guide until the catheter is in place, and then the guide is retracted from the vessel. In another application, a coil spring guide is first inserted into a catheter with the rounded tip of the guide extending beyond the distal end of the catheter. Then, this assembly is inserted into a vessel with the rounded tip of the coil spring guide facilitating placement of the guide and catheter tubing in the vessel without puncturing of the vessel. Once in place, the coil spring guide may be retracted, leaving the catheter in the vessel.
It is desirable in using such guidewires to provide some steering means, such as means for deflecting the tip of the guide to facilitate movement of the guidewire around or through a curved path in the vessel. There have been a number of patents directed to different constructions intended to provide a deflectable or flexible tip in a coil spring guide or guidewire. For example, such constructions are set forth in Muller, U.S. Pat. Nos. 3,452,740 and 3,452,742 Stevens, 3,503,385, Cook, 3,521,620, Jeckel et al., 3,528,406, Cook, 3,547,103, Muller, 3,625,200, Antoshkiw, 3,789,841, Tate, 3,841,308, Fleischhacker, 3,906,938, Fleischhacker et al., 3,973,556, Heilman, 4,003,369, Willson, 4,020,829, Willson et al., 4,215,703, Miles, 4,456,017, Samson et al., 4,538,622, Leary, 4,545,390, Samson et al., 4,554,929, and Morrison, 4,619,274, all of which are incorporated herein by reference.
While each of the above-mentioned patents provides guidewires having some steerability or flexibility, there is a need to develop a guidewire having better steerability. More particularly, there has been a need to develop a small diameter guidewire wherein its distal tip can be rotated and deflected to impart enhanced steerability suitable for cardiovascular applications.